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# CGDisplaySetStereoOperation(_:_:_:_:)

Immediately enables or disables stereo operation for a display.

```
func CGDisplaySetStereoOperation(_ display: CGDirectDisplayID, _ stereo: boolean_t, _ forceBlueLine: boolean_t, _ option: CGConfigureOption) -> CGError
```

## Parameters

`display`

The identifier of the display being configured.

`stereo`

Pass `true` if you want to enable stereo operation. To disable it, pass `false`.

`forceBlueLine`

When in stereo operation, a display may need to generate a special stereo sync signal as part of the video output.  The sync signal consists of a blue line that occupies the first 25% of the last scan line (for the left eye view), and the first 75% of the last scan line (for the right eye view). The remainder of the scan line is black. To force the display to generate this sync signal, pass `true`; otherwise pass `false`.

`option`

A constant that specifies the scope of the display configuration changes. For more information, see `Display Configuration Scopes`.

## Return Value

A result code. See `Core Graphics Data Types and Constants`.

## Discussion

The system normally detects the presence of a stereo window and automatically switches a display containing a stereo window to stereo operation. This function forces a display to stereo operation immediately, and sets options (blue line sync signal) when in stereo operation.

On success, the display resolution, mirroring mode, and available display modes may change due to hardware-specific capabilities and limitations. You should check these settings to verify that they are appropriate for your application.

---

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